⟦aa50e8084⟧

TextFile

% Change file for TeX in C, derived from various other change files.
% By Tim Morgan, UC Irvine ICS Department, and many others.
%
%
% Modification history:
%
% (05/28/86) ETM Started with TeX 2.0
% (06/03/87) ETM Brought up to TeX 2.2
% (09/26/87) ETM Brought up to TeX 2.3
% (10/01/87) ETM Brought up to TeX 2.5
% (12/21/87) ETM Brought up to TeX 2.7
% (01/14/88) ETM Brought up to TeX 2.9
% (02/20/88) PAM Revised format and module numbers
% (03/01/88) ETM Eliminated some unused variables and unnecesary tests
% (05/09/88) ETM Added yet another casting bug fix
% (06/21/88) ETM Brought up to TeX version 2.93
% (12/11/88) ETM Brought up to TeX version 2.94
% (01/12/89) PAM Brought up to TeX version 2.95
% (02/14/89) ETM Brought up to TeX version 2.96
% (03/10/89) ETM Brought up to TeX version 2.98
% (07/06/89) ETM Brought up to TeX version 2.991
% (11/30/89) KB  To version 2.992 (8-bit).
% (01/10/90) SR  To version 2.993.
% (03/27/90) KY  To version 3.0.
% 
% NOTE: the module numbers in this change file refer to the published
%	text in TeX: The Program, Volume B of Computers&Typesetting, 1986.


%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% [0] WEAVE: only print changes
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@x Tell WEAVE to print only the changes:
  \def\?##1]{\hbox to 1in{\hfil##1.\ }}
  }
@y
  \def\?##1]{\hbox{Changes to \hbox to 1em{\hfil##1}.\ }}
  }
\let\maybe=\iffalse
@z

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% [1.2] banner line
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@x
@d banner=='This is TeX, Version 3.0' {printed when \TeX\ starts}
@y
@d banner=='This is TeX-Xet, C Version 3.0' {printed when \TeX\ starts}
@z

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% [1.4] program header
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@x
Actually the heading shown here is not quite normal: The |program| line
does not mention any |output| file, because \ph\ would ask the \TeX\ user
to specify a file name if |output| were specified here.
@^system dependencies@>

@d mtype==t@&y@&p@&e {this is a \.{WEB} coding trick:}
@f mtype==type {`\&{mtype}' will be equivalent to `\&{type}'}
@f type==true {but `|type|' will not be treated as a reserved word}

@p @t\4@>@<Compiler directives@>@/
program TEX; {all file names are defined dynamically}
label @<Labels in the outer block@>@/
@y

@d mtype==t@&y@&p@&e {this is a \.{WEB} coding trick:}
@f mtype==type {`\&{mtype}' will be equivalent to `\&{type}'}
@f type==true {but `|type|' will not be treated as a reserved word}

@p @t\4@>@<Compiler directives@>@/
program TEXXET; {all file names are defined dynamically}
@z

@x
@<Labels in the out...@>=
start_of_TEX@t\hskip-2pt@>, end_of_TEX@t\hskip-2pt@>,@,final_end;
  {key control points}
@y
@<Labels in the outer block@>=
start_of_TEX@t\hskip-2pt@>, end_of_TEX@t\hskip-2pt@>,@,final_end;
  {key control points}
@z

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% [1.7] debug..gubed, stat..tats
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Here we change these WEB symbols, which are used much as #ifdef's
% in C, into something which will get translated into actual #ifdef's.
@x
@d debug==@{ {change this to `$\\{debug}\equiv\null$' when debugging}
@d gubed==@t@>@} {change this to `$\\{gubed}\equiv\null$' when debugging}
@y
@d debug==ifdef('DEBUG')
@d gubed==endif('DEBUG')
@z
@x
@d stat==@{ {change this to `$\\{stat}\equiv\null$' when gathering
  usage statistics}
@d tats==@t@>@} {change this to `$\\{tats}\equiv\null$' when gathering
  usage statistics}
@y
@d stat==ifdef('STAT')
@d tats==endif('STAT')
@z

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% [1.8] init..tini
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@x
@d init== {change this to `$\\{init}\equiv\.{@@\{}$' in the production version}
@d tini== {change this to `$\\{tini}\equiv\.{@@\}}$' in the production version}
@y
@d init==ifdef('INITEX')
@d tini==endif('INITEX')
@z

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% [1.9] compiler directives
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@x
@{@&$C-,A+,D-@} {no range check, catch arithmetic overflow, no debug overhead}
@!debug @{@&$C+,D+@}@+ gubed {but turn everything on when debugging}
@y
@z

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% [1.11] compile-time constants; mem_max enlarged, dvi_buf_size 16K for
% BSD I/O, others enlarged.  file_name_size becomes FILENAMESIZE.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@x
@<Constants...@>=
@!mem_max=30000; {greatest index in \TeX's internal |mem| array;
  must be strictly less than |max_halfword|;
  must be equal to |mem_top| in \.{INITEX}, otherwise |>=mem_top|}
@!mem_min=0; {smallest index in \TeX's internal |mem| array;
  must be |min_halfword| or more;
  must be equal to |mem_bot| in \.{INITEX}, otherwise |<=mem_bot|}
@!buf_size=500; {maximum number of characters simultaneously present in
  current lines of open files and in control sequences between
  \.{\\csname} and \.{\\endcsname}; must not exceed |max_halfword|}
@!error_line=72; {width of context lines on terminal error messages}
@!half_error_line=42; {width of first lines of contexts in terminal
  error messages; should be between 30 and |error_line-15|}
@!max_print_line=79; {width of longest text lines output; should be at least 60}
@!stack_size=200; {maximum number of simultaneous input sources}
@!max_in_open=6; {maximum number of input files and error insertions that
  can be going on simultaneously}
@!font_max=75; {maximum internal font number; must not exceed |max_quarterword|
  and must be at most |font_base+256|}
@!font_mem_size=20000; {number of words of |font_info| for all fonts}
@!param_size=60; {maximum number of simultaneous macro parameters}
@!nest_size=40; {maximum number of semantic levels simultaneously active}
@!max_strings=3000; {maximum number of strings; must not exceed |max_halfword|}
@!string_vacancies=8000; {the minimum number of characters that should be
  available for the user's control sequences and font names,
  after \TeX's own error messages are stored}
@!pool_size=32000; {maximum number of characters in strings, including all
  error messages and help texts, and the names of all fonts and
  control sequences; must exceed |string_vacancies| by the total
  length of \TeX's own strings, which is currently about 23000}
@!save_size=600; {space for saving values outside of current group; must be
  at most |max_halfword|}
@!trie_size=8000; {space for hyphenation patterns; should be larger for
  \.{INITEX} than it is in production versions of \TeX}
@!trie_op_size=500; {space for ``opcodes'' in the hyphenation patterns}
@!dvi_buf_size=800; {size of the output buffer; must be a multiple of 8}
@!file_name_size=40; {file names shouldn't be longer than this}
@!pool_name='TeXformats:TEX.POOL                     ';
  {string of length |file_name_size|; tells where the string pool appears}
@y
@d file_name_size == FILENAMESIZE {Get value from \.{site.h}.}
@<Constants...@>=
@!mem_max=262140; {greatest index in \TeX's internal |mem| array;
  must be strictly less than |max_halfword|;
  must be equal to |mem_top| in \.{INITEX}, otherwise |>=mem_top|}
@!mem_min=0; {smallest index in \TeX's internal |mem| array;
  must be |min_halfword| or more;
  must be equal to |mem_bot| in \.{INITEX}, otherwise |<=mem_bot|}
@!buf_size=3000; {maximum number of characters simultaneously present in
  current lines of open files and in control sequences between
  \.{\\csname} and \.{\\endcsname}; must not exceed |max_halfword|}
@!error_line=79; {width of context lines on terminal error messages}
@!half_error_line=50; {width of first lines of contexts in terminal
  error messages; should be between 30 and |error_line-15|}
@!max_print_line=79; {width of longest text lines output; should be at least 60}
@!stack_size=300; {maximum number of simultaneous input sources}
@!max_in_open=15; {maximum number of input files and error insertions that
  can be going on simultaneously}
@!font_max=255; {maximum internal font number; must not exceed |max_quarterword|
  and must be at most |font_base+256|}
@!font_mem_size=72000; {number of words of |font_info| for all fonts}
@!param_size=60; {maximum number of simultaneous macro parameters}
@!nest_size=40; {maximum number of semantic levels simultaneously active}
@!max_strings=7500; {maximum number of strings; must not exceed |max_halfword|}
@!string_vacancies=74000; {the minimum number of characters that should be
  available for the user's control sequences and font names,
  after \TeX's own error messages are stored}
@!pool_size=100000; {maximum number of characters in strings, including all
  error messages and help texts, and the names of all fonts and
  control sequences; must exceed |string_vacancies| by the total
  length of \TeX's own strings, which is currently about 23000}
@!save_size=4000; {space for saving values outside of current group; must be
  at most |max_halfword|}
@!trie_size=8000; {space for hyphenation patterns; should be larger for
  \.{INITEX} than it is in production versions of \TeX}
@!trie_op_size=500; {space for ``opcodes'' in the hyphenation patterns}
@!neg_trie_op_size=-500; {for lower trie_op_hash array bound}
@!dvi_buf_size=16384; {size of the output buffer; must be a multiple of 8}
@!pool_name='texxet.pool';
  {string of length |file_name_size|; tells where the string pool appears}
@!mem_top=262140; {largest index in the |mem| array dumped by \.{INITEX};
  must be substantially larger than |mem_bot|
  and not greater than |mem_max|}
@z

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% [1.12] Sensitive compile-time constants.  For C we change mem_base and
% hi_mem_base to reflect our use of 0-origin vs pc's use of
% negative-origin.  Despite the fact that it is a ``sensitive''
% constants, we're going to make mem_top a #define in the C code for
% readability and ease of modification (it's up above).  (It needs to be
% changed for the trip test.)  Similarly, if hash_size and hash_prime
% (which are in this module) are changed from the defaults, ini_to_trip
% has to be changed to reflect the new numbers.  It is not so easy to
% make them #define's as well, because hash_size is used as a numeric
% macro to compute the value of frozen_control_sequence.  And so
% ini_to_trip would have to change the change file instead of the texd.h
% file.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@x
@d mem_bot=0 {smallest index in the |mem| array dumped by \.{INITEX};
  must not be less than |mem_min|}
@d mem_top==30000 {largest index in the |mem| array dumped by \.{INITEX};
  must be substantially larger than |mem_bot|
  and not greater than |mem_max|}
@d font_base=0 {smallest internal font number; must not be less
  than |min_quarterword|}
@d hash_size=2100 {maximum number of control sequences; it should be at most
  about |(mem_max-mem_min)/10|}
@d hash_prime=1777 {a prime number equal to about 85\pct! of |hash_size|}
@d hyph_size=307 {another prime; the number of \.{\\hyphenation} exceptions}
@y
@d mem_bot=0 {smallest index in the |mem| array dumped by \.{INITEX};
  must not be less than |mem_min|}
@d font_base=0 {smallest internal font number; must not be less
  than |min_quarterword|}
@d hash_size=9500 {maximum number of control sequences; it should be at most
  about |(mem_max-mem_min)/10|}
@d hash_prime=7919 {The thousandth in a list of 1000 primes.  Run the primes
  program in LiterateProgramming to find out.  It is reasonably close to
  85\pct! of a |hash_size| of 9500}
@d hyph_size=607 {another prime; the number of \.{\\hyphenation} exceptions}
@z

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% [1.16] Use C macros for incr()/decr()
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% By not defining these, they slip through into the C code, where we
% use macros, which we hope generate more efficient code.
@x
@d incr(#) == #:=#+1 {increase a variable by unity}
@d decr(#) == #:=#-1 {decrease a variable by unity}
@y
@z

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% [??] The text_char type is used as an array index into xord.  The
% default type `char' produces signed integers, which are bad array
% indices in C.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 

@x
@d text_char == char {the data type of characters in text files}
@y
@d text_char == ASCII_code {the data type of characters in text files}
@z

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% [2.23] allow any character that we can input to get in
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@x
for i:=0 to @'37 do xchr[i]:=' ';
for i:=@'177 to @'377 do xchr[i]:=' ';
@y
for i:=0 to @'37 do xchr[i]:=chr(i);
for i:=@'177 to @'377 do xchr[i]:=chr(i);
@z

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% [3.25] file types
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@x
The program actually makes use also of a third kind of file, called a
|word_file|, when dumping and reloading base information for its own
initialization.  We shall define a word file later; but it will be possible
for us to specify simple operations on word files before they are defined.

@y
I/O in C is done using standard I/O.  We will define the path numbers
in an include file for C which are used in searching for files to be
read.  We'll define all the file types in C also.
@z

@x
@!alpha_file=packed file of text_char; {files that contain textual data}
@!byte_file=packed file of eight_bits; {files that contain binary data}
@y
@z

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% [3.26] add real_name_of_file array
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@x
is crucial for our purposes. We shall assume that |name_of_file| is a variable
of an appropriate type such that the \PASCAL\ run-time system being used to
implement \TeX\ can open a file whose external name is specified by
|name_of_file|.
@^system dependencies@>

@<Glob...@>=
@!name_of_file:packed array[1..file_name_size] of char;@;@/
  {on some systems this may be a \&{record} variable}
@!name_length:0..file_name_size;@/{this many characters are actually
  relevant in |name_of_file| (the rest are blank)}
@y
is crucial for our purposes. We shall assume that |name_of_file| is a variable
of an appropriate type such that the \PASCAL\ run-time system being used to
implement \TeX\ can open a file whose external name is specified by
|name_of_file|.
The C version uses search paths to look for files to open.
We use |real_name_of_file| to hold the |name_of_file| with a directory
name from the path in front of it.
@^system dependencies@>

@<Glob...@>=
@!name_of_file,@!real_name_of_file:packed array[1..file_name_size] of char;
@;@/
@!name_length:0..file_name_size;@/{this many characters are actually
  relevant in |name_of_file| (the rest are blank)}
@z

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% [3.27] file opening
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@x
@ The \ph\ compiler with which the present version of \TeX\ was prepared has
extended the rules of \PASCAL\ in a very convenient way. To open file~|f|,
we can write
$$\vbox{\halign{#\hfil\qquad&#\hfil\cr
|reset(f,@t\\{name}@>,'/O')|&for input;\cr
|rewrite(f,@t\\{name}@>,'/O')|&for output.\cr}}$$
The `\\{name}' parameter, which is of type `{\bf packed array
$[\langle\\{any}\rangle]$ of \\{char}}', stands for the name of
the external file that is being opened for input or output.
Blank spaces that might appear in \\{name} are ignored.

The `\.{/O}' parameter tells the operating system not to issue its own
error messages if something goes wrong. If a file of the specified name
cannot be found, or if such a file cannot be opened for some other reason
(e.g., someone may already be trying to write the same file), we will have
|@!erstat(f)<>0| after an unsuccessful |reset| or |rewrite|.  This allows
\TeX\ to undertake appropriate corrective action.
@:PASCAL H}{\ph@>
@^system dependencies@>

\TeX's file-opening procedures return |false| if no file identified by
|name_of_file| could be opened.

@d reset_OK(#)==erstat(#)=0
@d rewrite_OK(#)==erstat(#)=0

@p function a_open_in(var f:alpha_file):boolean;
  {open a text file for input}
begin reset(f,name_of_file,'/O'); a_open_in:=reset_OK(f);
end;
@#
function a_open_out(var f:alpha_file):boolean;
  {open a text file for output}
begin rewrite(f,name_of_file,'/O'); a_open_out:=rewrite_OK(f);
end;
@#
function b_open_in(var f:byte_file):boolean;
  {open a binary file for input}
begin reset(f,name_of_file,'/O'); b_open_in:=reset_OK(f);
end;
@#
function b_open_out(var f:byte_file):boolean;
  {open a binary file for output}
begin rewrite(f,name_of_file,'/O'); b_open_out:=rewrite_OK(f);
end;
@#
function w_open_in(var f:word_file):boolean;
  {open a word file for input}
begin reset(f,name_of_file,'/O'); w_open_in:=reset_OK(f);
end;
@#
function w_open_out(var f:word_file):boolean;
  {open a word file for output}
begin rewrite(f,name_of_file,'/O'); w_open_out:=rewrite_OK(f);
end;
@y
@ All of the file opening functions will be defined as macros in C.
@z

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% [3.28] reserve file closure for C routines
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@x
@ Files can be closed with the \ph\ routine `|close(f)|', which
@^system dependencies@>
should be used when all input or output with respect to |f| has been completed.
This makes |f| available to be opened again, if desired; and if |f| was used for
output, the |close| operation makes the corresponding external file appear
on the user's area, ready to be read.

These procedures should not generate error messages if a file is
being closed before it has been successfully opened.

@p procedure a_close(var f:alpha_file); {close a text file}
begin close(f);
end;
@#
procedure b_close(var f:byte_file); {close a binary file}
begin close(f);
end;
@#
procedure w_close(var f:word_file); {close a word file}
begin close(f);
end;
@y
@ And all file closing as well.
@z

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% [3.31] Make input_ln an external C routine
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@x
@p function input_ln(var f:alpha_file;@!bypass_eoln:boolean):boolean;
  {inputs the next line or returns |false|}
var last_nonblank:0..buf_size; {|last| with trailing blanks removed}
begin if bypass_eoln then if not eof(f) then get(f);
  {input the first character of the line into |f^|}
last:=first; {cf.\ Matthew 19\thinspace:\thinspace30}
if eof(f) then input_ln:=false
else  begin last_nonblank:=first;
  while not eoln(f) do
    begin if last>=max_buf_stack then
      begin max_buf_stack:=last+1;
      if max_buf_stack=buf_size then
        @<Report overflow of the input buffer, and abort@>;
      end;
    buffer[last]:=xord[f^]; get(f); incr(last);
    if buffer[last-1]<>" " then last_nonblank:=last;
    end;
  last:=last_nonblank; input_ln:=true;
  end;
end;
@y
We'll get |input_ln| from an external C module, coded for efficiency
directly in C.
@z

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% [3.32] term_in/out are input,output.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@x
@ The user's terminal acts essentially like other files of text, except
that it is used both for input and for output. When the terminal is
considered an input file, the file variable is called |term_in|, and when it
is considered an output file the file variable is |term_out|.
@^system dependencies@>

@<Glob...@>=
@!term_in:alpha_file; {the terminal as an input file}
@!term_out:alpha_file; {the terminal as an output file}
@y
@ The user's terminal acts essentially like other files of text, except
that it is used both for input and for output. When the terminal is
considered an input file, the file is called |term_in|, and when it
is considered an output file the file is |term_out|.  In C, these
files will be defined as ``stdin'' and ``stdout,'' respectively.

@d term_in==stdin {the terminal as an input file}
@d term_out==stdout {the terminal as an output file}
@z

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% [3.33] don't need to open terminal files
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@x
@ Here is how to open the terminal files
in \ph. The `\.{/I}' switch suppresses the first |get|.
@^system dependencies@>

@d t_open_in==reset(term_in,'TTY:','/O/I') {open the terminal for text input}
@d t_open_out==rewrite(term_out,'TTY:','/O') {open the terminal for text output}
@y
@ Here is how to open the terminal files.  |t_open_out| does nothing.
|t_open_in|, on the other hand, does the work of "rescanning", or getting
any command line arguments the user has provided.  It's coded in C
externally.

@d t_open_out == {output already open for text output}
@z

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% [3.34] flushing output
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@x
these operations can be specified in \ph:
@^system dependencies@>

@d update_terminal == break(term_out) {empty the terminal output buffer}
@d clear_terminal == break_in(term_in,true) {clear the terminal input buffer}
@d wake_up_terminal == do_nothing {cancel the user's cancellation of output}
@y
these operations can be specified with {\mc UNIX}.  |update_terminal|
does an fflush, since that's easy.  |wake_up_terminal| and |clear_terminal|
are specified in external C routines, if desired.  We call |fflush()|
|termflush()| here, and fix it with a macro in C, so we can cast it to (void)
to keep lint quiet.
@^system dependencies@>

@d update_terminal == termflush(term_out)
@z

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% [3.37] rescanning the command line 
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@x
@ The following program does the required initialization
without retrieving a possible command line.
It should be clear how to modify this routine to deal with command lines,
if the system permits them.
@^system dependencies@>

@p function init_terminal:boolean; {gets the terminal input started}
label exit;
begin t_open_in;
loop@+begin wake_up_terminal; write(term_out,'**'); update_terminal;
@.**@>
  if not input_ln(term_in,true) then {this shouldn't happen}
    begin write_ln(term_out);
    write(term_out,'! End of file on the terminal... why?');
@.End of file on the terminal@>
    init_terminal:=false; return;
    end;
  loc:=first;
  while (loc<last)and(buffer[loc]=" ") do incr(loc);
  if loc<last then
    begin init_terminal:=true;
    return; {return unless the line was all blank}
    end;
  write_ln(term_out,'Please type the name of your input file.');
  end;
exit:end;
@y
@ The following program does the required initialization.
Iff anything has been specified on the command line, then |t_open_in|
will return with |last > first|.
@^system dependencies@>

@p
function init_terminal:boolean; {gets the terminal input started}
label exit;
begin
    t_open_in;
    if last > first then begin
        loc := first;
        while (loc < last) and (buffer[loc]=' ') do
	    incr(loc);
        if loc < last then begin
            init_terminal := true;
            goto exit;
        end;
    end;
    loop@+begin
        wake_up_terminal; write(term_out, '**'); update_terminal;
@.**@>
        if not input_ln(term_in,true) then begin {this shouldn't happen}
            write_ln(term_out);
            write(term_out, '! End of file on the terminal... why?');
@.End of file on the terminal@>
            init_terminal:=false;
	    return;
        end;

        loc:=first;
        while (loc<last)and(buffer[loc]=" ") do
            incr(loc);

        if loc<last then begin
           init_terminal:=true;
           return; {return unless the line was all blank}
        end;
        write_ln(term_out, 'Please type the name of your input file.');
    end;
exit:
end;
@z

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% [4.51] a_open_in of pool file needs path specifier
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@x
name_of_file:=pool_name; {we needn't set |name_length|}
if a_open_in(pool_file) then
@y
vstrcpy(name_of_file+1, pool_name); {this is how you copy strings in C}
if a_open_in(pool_file,pool_path_spec) then
@z

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% [4.51,52,53] make TEX.POOL lowercase in messages; fix reading it
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@x
else  bad_pool('! I can''t read TEX.POOL.')
@y
else begin
   {Like |bad_pool|, but must not close file if we never opened it}
   wake_up_terminal; write_ln(term_out, '! I can''t read texxet.pool.');
   get_strings_started:= false; return;
end
@z
@x
begin if eof(pool_file) then bad_pool('! TEX.POOL has no check sum.');
@.TEX.POOL has no check sum@>
read(pool_file,m,n); {read two digits of string length}
@y
begin if eof(pool_file) then bad_pool('! texxet.pool has no check sum.');
@.TEX.POOL has no check sum@>
read(pool_file,m); read(pool_file,n); {read two digits of string length}
@z
@x
    bad_pool('! TEX.POOL line doesn''t begin with two digits.');
@y
    bad_pool('! texxet.pool line doesn''t begin with two digits.');
@z
@x
  bad_pool('! TEX.POOL check sum doesn''t have nine digits.');
@y
  bad_pool('! texxet.pool check sum doesn''t have nine digits.');
@z
@x
done: if a<>@$ then bad_pool('! TEX.POOL doesn''t match; TANGLE me again.');
@y
done: if a<>@$ then bad_pool('! texxet.pool doesn''t match; tangle me again.');
@z

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% [5.61] Eliminate the misleading terminal message ``(no format preloaded)''.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@x
if format_ident=0 then wterm_ln(' (no format preloaded)')
else  begin print(format_ident); print_ln;
  end;
@y
if format_ident>0 then print(format_ident); 
print_ln;
@z

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% [6.81] Eliminate nonlocal goto
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% C cannot do non-local goto's.
% Plus, it's nicer just to do an exit with the appropriate status code
% under Unix.  We call it |uexit| because there's a WEB symbol called
% |exit| already.  We use a C macro to change |uexit()| back to |exit()|.
@x
@<Error hand...@>=
procedure jump_out;
begin goto end_of_TEX;
end;
@y
@d do_final_end==begin
   update_terminal;
   ready_already:=0;
   if (history <> spotless) and (history <> warning_issued) then
       uexit(1)
   else
       uexit(0);
   end
@<Error hand...@>=
procedure jump_out;
begin
close_files_and_terminate;
do_final_end;
end;
@z

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% [6.84] switch-to-editor option
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@x
line ready to be edited. But such an extension requires some system
wizardry, so the present implementation simply types out the name of the
file that should be
edited and the relevant line number.
@^system dependencies@>

There is a secret `\.D' option available when the debugging routines haven't 
been commented~out.
@^debugging@>
@y
line ready to be edited.
We do this by calling the external procedure |calledit| with a pointer to
the filename, its length, and the line number.
However, here we just set up the variables that will be used as arguments,
since we don't want to do the switch-to-editor until after TeX has closed
its files.
@^system dependencies@>

There is a secret `\.D' option available when the debugging routines haven't
been commented~out.
@^debugging@>
@d edit_file==input_stack[base_ptr]
@z
@x
"E": if base_ptr>0 then
  begin print_nl("You want to edit file ");
@.You want to edit file x@>
  print(input_stack[base_ptr].name_field);
  print(" at line "); print_int(line);
  interaction:=scroll_mode; jump_out;
@y
"E": if base_ptr>0 then
    begin
    edit_name_start:=str_start[edit_file.name_field];
    edit_name_length:=str_start[edit_file.name_field+1] -
    		      str_start[edit_file.name_field];
    edit_line:=line;
    jump_out;
@z

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% [7.109] Handle definition of glue_ratio in an include file as a typedef
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@x
@!glue_ratio=real; {one-word representation of a glue expansion factor}
@y
@z

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% [8.110] Make it easy to build a bigger TeX.  (Nothing is changed in
% the basic version.)
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@x
@d min_quarterword=0 {smallest allowable value in a |quarterword|}
@d max_quarterword=255 {largest allowable value in a |quarterword|}
@d min_halfword==0 {smallest allowable value in a |halfword|}
@d max_halfword==65535 {largest allowable value in a |halfword|}
@y
@d min_quarterword=0 {smallest allowable value in a |quarterword|}
@d max_quarterword=511 {largest allowable value in a |quarterword|}
@d min_halfword==0 {smallest allowable value in a |halfword|}
@d max_halfword==262143 {largest allowable value in a |halfword|}
@z

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% [8.112] Efficiency!
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@x
The inner loop of \TeX\ will run faster with respect to compilers
that don't optimize expressions like `|x+0|' and `|x-0|', if these
macros are simplified in the obvious way when |min_quarterword=0|.
@^inner loop@>@^system dependencies@>

@d qi(#)==#+min_quarterword
  {to put an |eight_bits| item into a quarterword}
@d qo(#)==#-min_quarterword
  {to take an |eight_bits| item out of a quarterword}
@d hi(#)==#+min_halfword
  {to put a sixteen-bit item into a halfword}
@d ho(#)==#-min_halfword
  {to take a sixteen-bit item from a halfword}
@y
The inner loop of \TeX\ will run faster with respect to compilers
that don't optimize expressions like `|x+0|' and `|x-0|', if these
macros are simplified in the obvious way when |min_quarterword=0|.
So they have been simplified here in the obvious way.
@^inner loop@>@^system dependencies@>

@d qi(#)==# {to put an |eight_bits| item into a quarterword}
@d qo(#)==# {to take an |eight_bits| item from a quarterword}
@d hi(#)==# {to put a sixteen-bit item into a halfword}
@d ho(#)==# {to take a sixteen-bit item from a halfword}
@z

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% [8.113] Put the memory structure into an include file; it's too hard
% to translate automatically.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@x
@!quarterword = min_quarterword..max_quarterword; {1/4 of a word}
@!halfword=min_halfword..max_halfword; {1/2 of a word}
@!two_choices = 1..2; {used when there are two variants in a record}
@!four_choices = 1..4; {used when there are four variants in a record}
@!two_halves = packed record@;@/
  @!rh:halfword;
  case two_choices of
  1: (@!lh:halfword);
  2: (@!b0:quarterword; @!b1:quarterword);
  end;
@!four_quarters = packed record@;@/
  @!b0:quarterword;
  @!b1:quarterword;
  @!b2:quarterword;
  @!b3:quarterword;
  end;
@!memory_word = record@;@/
  case four_choices of
  1: (@!int:integer);
  2: (@!gr:glue_ratio);
  3: (@!hh:two_halves);
  4: (@!qqqq:four_quarters);
  end;
@!word_file = file of memory_word;
@y
@!quarterword=min_quarterword..max_quarterword;
@!halfword=min_halfword..max_halfword;
@!two_choices = 1..2; {used when there are two variants in a record}
@!four_choices = 1..4; {used when there are four variants in a record}
@=#include "memory.h";@>
@z

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% [9.116] Change mem to zmem
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% We do this so that we can define mem to be a register pointer to the
% memory array for speed.
@x
@!mem : array[mem_min..mem_max] of memory_word; {the big dynamic storage area}
@y
@!zmem : array[mem_min..mem_max] of memory_word; {the big dynamic storage area}
@z

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% [9.127] Fix casting problem in C.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% There are several of these.  They come from the rules C uses for
% comparing signed and unsigned quantities.  Just doing the comparison
% can result in incorrect evaluation wrt the way Pascal would do it.
@x
if r>p+1 then @<Allocate from the top of node |p| and |goto found|@>;
@y
if r>toint(p+1) then @<Allocate from the top of node |p| and |goto found|@>;
@z

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% [10.161] make room for a new creation procedure (TeX-XeT extension)
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@x 
\TeX's other algorithms intact.
@^system dependencies@>
@y
\TeX's other algorithms intact.
@^system dependencies@>
@p@<Declare functions needed for special kinds of nodes@>
@z

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% [11.165] Fix the word `free' so that it doesn't conflict with the
% standard C library routine of the same name.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@x
been included. (You may want to decrease the size of |mem| while you
@^debugging@>
are debugging.)
@y
been included. (You may want to decrease the size of |mem| while you
@^debugging@>
are debugging.)

@d free==free_arr
@z

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% [12.174] Eliminate some unsigned comparisons to zero
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@x
        begin if (font(p)<font_base)or(font(p)>font_max) then
          print_char("*")
@y
        begin if (font(p)>font_max) then
          print_char("*")
@z

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% [12.176] Eliminate some unsigned comparisons to zero (continued)
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@x
@p procedure print_font_and_char(@!p:integer); {prints |char_node| data}
begin if p>mem_end then print_esc("CLOBBERED.")
else  begin if (font(p)<font_base)or(font(p)>font_max) then print_char("*")
@y
@p procedure print_font_and_char(@!p:integer); {prints |char_node| data}
begin if p>mem_end then print_esc("CLOBBERED.")
else  begin if (font(p)>font_max) then print_char("*")
@z

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% [12.186] glue_ratio fix
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@x
floating point underflow on the author's computer.
@^system dependencies@>
@^dirty \PASCAL@>

@<Display the value of |glue_set(p)|@>=
g:=float(glue_set(p));
if (g<>float_constant(0))and(glue_sign(p)<>normal) then
  begin print(", glue set ");
  if glue_sign(p)=shrinking then print("- ");
  if abs(mem[p+glue_offset].int)<@'4000000 then print("?.?")
  else if abs(g)>float_constant(20000) then
    begin if g>float_constant(0) then print_char(">")
    else print("< -");
    print_glue(20000*unity,glue_order(p),0);
    end
  else print_glue(round(unity*g),glue_order(p),0);
@^real multiplication@>
  end
@y
floating point underflow on the author's computer.
@^system dependencies@>
@^dirty \PASCAL@>

@<Display the value of |glue_set(p)|@>=
g:=float(glue_set(p));
if (g<>float_constant(0))and(glue_sign(p)<>normal) then
  begin print(", glue set ");
  if glue_sign(p)=shrinking then print("- ");
  { The Unix "pc" folks removed this restriction with a remark that
    invalid bit patterns were vanishingly improbable, so we follow
    their example without really understanding it.
  |if abs(mem[p+glue_offset].int)<@'4000000 then print('?.?')|
  |else| }
  if fabs(g)>float_constant(20000) then
    begin if g>float_constant(0) then print_char(">")
    else print("< -");
    print_glue(20000*unity,glue_order(p),0);
    end
  else print_glue(round(unity*g),glue_order(p),0);
@^real multiplication@>
  end
@z

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% [15.208,209] New command code (TeX-XeT extension)
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@x 
@d max_non_prefixed_command=70 {largest command code that can't be \.{\\global}}

@ The next codes are special; they all relate to mode-independent
assignment of values to \TeX's internal registers or tables.
Codes that are |max_internal| or less represent internal quantities
that might be expanded by `\.{\\the}'.

@d toks_register=71 {token list register ( \.{\\toks} )}
@d assign_toks=72 {special token list ( \.{\\output}, \.{\\everypar}, etc.~)}
@d assign_int=73 {user-defined integer ( \.{\\tolerance}, \.{\\day}, etc.~)}
@d assign_dimen=74 {user-defined length ( \.{\\hsize}, etc.~)}
@d assign_glue=75 {user-defined glue ( \.{\\baselineskip}, etc.~)}
@d assign_mu_glue=76 {user-defined muglue ( \.{\\thinmuskip}, etc.~)}
@d assign_font_dimen=77 {user-defined font dimension ( \.{\\fontdimen} )}
@d assign_font_int=78 {user-defined font integer ( \.{\\hyphenchar},
  \.{\\skewchar} )}
@d set_aux=79 {specify state info ( \.{\\spacefactor}, \.{\\prevdepth} )}
@d set_prev_graf=80 {specify state info ( \.{\\prevgraf} )}
@d set_page_dimen=81 {specify state info ( \.{\\pagegoal}, etc.~)}
@d set_page_int=82 {specify state info ( \.{\\deadcycles},
  \.{\\insertpenalties} )}
@d set_box_dimen=83 {change dimension of box ( \.{\\wd}, \.{\\ht}, \.{\\dp} )}
@d set_shape=84 {specify fancy paragraph shape ( \.{\\parshape} )}
@d def_code=85 {define a character code ( \.{\\catcode}, etc.~)}
@d def_family=86 {declare math fonts ( \.{\\textfont}, etc.~)}
@d set_font=87 {set current font ( font identifiers )}
@d def_font=88 {define a font file ( \.{\\font} )}
@d register=89 {internal register ( \.{\\count}, \.{\\dimen}, etc.~)}
@d max_internal=89 {the largest code that can follow \.{\\the}}
@d advance=90 {advance a register or parameter ( \.{\\advance} )}
@d multiply=91 {multiply a register or parameter ( \.{\\multiply} )}
@d divide=92 {divide a register or parameter ( \.{\\divide} )}
@d prefix=93 {qualify a definition ( \.{\\global}, \.{\\long}, \.{\\outer} )}
@d let=94 {assign a command code ( \.{\\let}, \.{\\futurelet} )}
@d shorthand_def=95 {code definition ( \.{\\chardef}, \.{\\countdef}, etc.~)}
@d read_to_cs=96 {read into a control sequence ( \.{\\read} )}
@d def=97 {macro definition ( \.{\\def}, \.{\\gdef}, \.{\\xdef}, \.{\\edef} )}
@d set_box=98 {set a box ( \.{\\setbox} )}
@d hyph_data=99 {hyphenation data ( \.{\\hyphenation}, \.{\\patterns} )}
@d set_interaction=100 {define level of interaction ( \.{\\batchmode}, etc.~)}
@d max_command=100 {the largest command code seen at |big_switch|}
@y
@d LR=71 {text direction ( \.{\\beginL}, \.{\\beginR}, \.{\\endL}, \.{\\endR} )}
@d max_non_prefixed_command=71 {largest command code that can't be \.{\\global}}

@ The next codes are special; they all relate to mode-independent
assignment of values to \TeX's internal registers or tables.
Codes that are |max_internal| or less represent internal quantities
that might be expanded by `\.{\\the}'.

@d toks_register=72 {token list register ( \.{\\toks} )}
@d assign_toks=73 {special token list ( \.{\\output}, \.{\\everypar}, etc.~)}
@d assign_int=74 {user-defined integer ( \.{\\tolerance}, \.{\\day}, etc.~)}
@d assign_dimen=75 {user-defined length ( \.{\\hsize}, etc.~)}
@d assign_glue=76 {user-defined glue ( \.{\\baselineskip}, etc.~)}
@d assign_mu_glue=77 {user-defined muglue ( \.{\\thinmuskip}, etc.~)}
@d assign_font_dimen=78 {user-defined font dimension ( \.{\\fontdimen} )}
@d assign_font_int=79 {user-defined font integer ( \.{\\hyphenchar},
  \.{\\skewchar} )}
@d set_aux=80 {specify state info ( \.{\\spacefactor}, \.{\\prevdepth} )}
@d set_prev_graf=81 {specify state info ( \.{\\prevgraf} )}
@d set_page_dimen=82 {specify state info ( \.{\\pagegoal}, etc.~)}
@d set_page_int=83 {specify state info ( \.{\\deadcycles},
  \.{\\insertpenalties} )}
@d set_box_dimen=84 {change dimension of box ( \.{\\wd}, \.{\\ht}, \.{\\dp} )}
@d set_shape=85 {specify fancy paragraph shape ( \.{\\parshape} )}
@d def_code=86 {define a character code ( \.{\\catcode}, etc.~)}
@d def_family=87 {declare math fonts ( \.{\\textfont}, etc.~)}
@d set_font=88 {set current font ( font identifiers )}
@d def_font=89 {define a font file ( \.{\\font} )}
@d register=90 {internal register ( \.{\\count}, \.{\\dimen}, etc.~)}
@d max_internal=90 {the largest code that can follow \.{\\the}}
@d advance=91 {advance a register or parameter ( \.{\\advance} )}
@d multiply=92 {multiply a register or parameter ( \.{\\multiply} )}
@d divide=93 {divide a register or parameter ( \.{\\divide} )}
@d prefix=94 {qualify a definition ( \.{\\global}, \.{\\long}, \.{\\outer} )}
@d let=95 {assign a command code ( \.{\\let}, \.{\\futurelet} )}
@d shorthand_def=96 {code definition ( \.{\\chardef}, \.{\\countdef}, etc.~)}
@d read_to_cs=97 {read into a control sequence ( \.{\\read} )}
@d def=98 {macro definition ( \.{\\def}, \.{\\gdef}, \.{\\xdef}, \.{\\edef} )}
@d set_box=99 {set a box ( \.{\\setbox} )}
@d hyph_data=100 {hyphenation data ( \.{\\hyphenation}, \.{\\patterns} )}
@d set_interaction=101 {define level of interaction ( \.{\\batchmode}, etc.~)}
@d max_command=101 {the largest command code seen at |big_switch|}
@z

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% [17.241] fix_date_and_time
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@x
@ The following procedure, which is called just before \TeX\ initializes its
input and output, establishes the initial values of the date and time.
@^system dependencies@>
Since standard \PASCAL\ cannot provide such information, something special
is needed. The program here simply specifies July 4, 1776, at noon; but
users probably want a better approximation to the truth.

@p procedure fix_date_and_time;
begin time:=12*60; {minutes since midnight}
day:=4; {fourth day of the month}
month:=7; {seventh month of the year}
year:=1776; {Anno Domini}
end;
@y
@ The following procedure, which is called just before \TeX\ initializes its
input and output, establishes the initial values of the date and time.
It calls a macro-defined |date_and_time| routine.  |date_and_time|
("dateandtime") in turn is a C macro, which calls |get_date_and_time|, passing
it the addresses of the day, month, etc., so they can be set by the
routine.  |get_date_and_time| also sets up interrupt catching if that
is conditionally compiled in the C code.
@^system dependencies@>

@d fix_date_and_time==date_and_time(time,day,month,year)
@z

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% [17.253] Change eqtb to zeqtb
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@x
@!eqtb:array[active_base..eqtb_size] of memory_word;
@y
@!zeqtb:array[active_base..eqtb_size] of memory_word;
@z

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% [18.262] More useless unsigned comparisons to zero
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@x
else if (text(p)<0)or(text(p)>=str_ptr) then print_esc("NONEXISTENT.")
@y
else if (text(p)>=str_ptr) then print_esc("NONEXISTENT.")
@z

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% [23.331] use a different for loop index, local to tex_body
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@x
first:=buf_size; repeat buffer[first]:=0; decr(first); until first=0;
@y
bufindx:=buf_size; repeat buffer[bufindx]:=0; decr(bufindx); until bufindx=0;
@z

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% [29.513] area and extension rules
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@x
@ The file names we shall deal with for illustrative purposes have the
following structure:  If the name contains `\.>' or `\.:', the file area
consists of all characters up to and including the final such character;
otherwise the file area is null.  If the remaining file name contains
`\..', the file extension consists of all such characters from the first
remaining `\..' to the end, otherwise the file extension is null.
@^system dependencies@>

We can scan such file names easily by using two global variables that keep track
of the occurrences of area and extension delimiters:

@<Glob...@>=
@!area_delimiter:pool_pointer; {the most recent `\.>' or `\.:', if any}
@!ext_delimiter:pool_pointer; {the relevant `\..', if any}
@y
@ The file names we shall deal with for illustrative purposes have the
following structure:  If the name contains `\./', the file area
consists of all characters up to and including the final such character;
otherwise the file area is null.  If the remaining file name contains
`\..', the file extension consists of all such characters from the last
`\..' to the end, otherwise the file extension is null.
@^system dependencies@>

We can scan such file names easily by using two global variables that keep
track of the occurrences of area and extension delimiters:

@<Glob...@>=
@!area_delimiter:pool_pointer; {the most recent `\./', if any}
@!ext_delimiter:pool_pointer; {the most recent `\..', if any}
@z

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% [29.514] TEX area directories
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@x
@d TEX_area=="TeXinputs:"
@.TeXinputs@>
@d TEX_font_area=="TeXfonts:"
@.TeXfonts@>
@y
We'll handle the path stuff in an external C module.
@z

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% [29.516] more_name
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@x
else  begin str_room(1); append_char(c); {contribute |c| to the current string}
  if (c=">")or(c=":") then
    begin area_delimiter:=cur_length; ext_delimiter:=0;
    end
  else if (c=".")and(ext_delimiter=0) then ext_delimiter:=cur_length;
@y
else  begin str_room(1); append_char(c); {contribute |c| to the current string}
  if (c="/") then
    begin area_delimiter:=cur_length; ext_delimiter:=0;
    end
  else if c="." then ext_delimiter:=cur_length;
@z

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% [29.520] default format
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@x
@d format_default_length=20 {length of the |TEX_format_default| string}
@d format_area_length=11 {length of its area part}
@d format_ext_length=4 {length of its `\.{.fmt}' part}
@y
Under {\mc UNIX} we don't give the area part, instead depending
on the path searching that will happen during file opening.

@d format_default_length=9 {length of the |TEX_format_default| string}
@d format_area_length=0 {length of its area part}
@d format_ext_length=4 {length of its `\.{.fmt}' part}
@z

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% [29.521] plain format location
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@x
@!TEX_format_default:packed array[1..format_default_length] of char;

@ @<Set init...@>=
TEX_format_default:='TeXformats:plain.fmt';
@y
@!TEX_format_default:c_char_pointer;

@ @<Set init...@>=
TEX_format_default := ' plain.fmt';
@z

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% [29.524] format file opening: only try once, with path search
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@x
  pack_buffered_name(0,loc,j-1); {try first without the system file area}
  if w_open_in(fmt_file) then goto found;
  pack_buffered_name(format_area_length,loc,j-1);
    {now try the system format file area}
  if w_open_in(fmt_file) then goto found;
@y
  pack_buffered_name(0,loc,j-1);
  if w_open_in(fmt_file) then goto found;
@z

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% (still [29.524]) replace `PLAIN' in error messages with `default'.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@x
  wterm_ln('Sorry, I can''t find that format;',' will try PLAIN.');
@y
  wterm_ln('Sorry, I can''t find that format;',' will try the default.');
@z
@x
  wterm_ln('I can''t find the PLAIN format file!');
@.I can't find PLAIN...@>
@y
  wterm_ln('I can''t find the default format file!');
@.I can't find default format...@>
@z

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% [29.525] make_name_string
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@x
which simply makes a \TeX\ string from the value of |name_of_file|, should
ideally be changed to deduce the full name of file~|f|, which is the file
most recently opened, if it is possible to do this in a \PASCAL\ program.
@^system dependencies@>

This routine might be called after string memory has overflowed, hence
we dare not use `|str_room|'.

@p function make_name_string:str_number;
var k:1..file_name_size; {index into |name_of_file|}
begin if (pool_ptr+name_length>pool_size)or(str_ptr=max_strings)or
 (cur_length>0) then
  make_name_string:="?"
else  begin for k:=1 to name_length do append_char(xord[name_of_file[k]]);
  make_name_string:=make_string;
  end;
end;
function a_make_name_string(var f:alpha_file):str_number;
begin a_make_name_string:=make_name_string;
end;
function b_make_name_string(var f:byte_file):str_number;
begin b_make_name_string:=make_name_string;
end;
function w_make_name_string(var f:word_file):str_number;
begin w_make_name_string:=make_name_string;
end;
@y
which simply makes a \TeX\ string from the value of |name_of_file|, should
ideally be changed to deduce the full name of file~|f|, if it is
possible to do this in a \PASCAL\ program.

This routine might be called after string memory has overflowed, hence
we dare not use `|str_room|'.

With the C version, we know that |real_name_of_file|
contains |name_of_file| prepended with the directory name that was found
by path searching.

If |real_name_of_file| starts with |'./'|, we don't use that part of the
name, since {\mc UNIX} users understand that.
@^system dependencies@>

@p function make_name_string:str_number;
var k,@!kstart:1..file_name_size; {index into |name_of_file|}
begin
  k:=1;
  while (k<file_name_size) and (xord[real_name_of_file[k]]<>" ") do
    incr(k);
  name_length:=k-1; {the real |name_length|}
  if (pool_ptr+name_length>pool_size)or(str_ptr=max_strings)or
   (cur_length>0) then
    make_name_string:="?"
  else begin
    if (xord[real_name_of_file[1]]=".")and(xord[real_name_of_file[2]]="/") then
      kstart:=3
    else
      kstart:=1;
    for k:=kstart to name_length do append_char(xord[real_name_of_file[k]]);
    make_name_string:=make_string;
  end;
end;

{The X_make_name_string functions are changed to macros in C.}
@z

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% [29.534] Adjust for C string conventions
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

@x
@!months:packed array [1..36] of char; {abbreviations of month names}
@y
@!months:c_char_pointer;
@z

@x
months:='JANFEBMARAPRMAYJUNJULAUGSEPOCTNOVDEC';
@y
months := ' JANFEBMARAPRMAYJUNJULAUGSEPOCTNOVDEC';
@z

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% [29.537] a_open_in of \input file needs path selector
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@x
  if a_open_in(cur_file) then goto done;
  if cur_area="" then
    begin pack_file_name(cur_name,TEX_area,cur_ext);
    if a_open_in(cur_file) then goto done;
    end;
@y
  if a_open_in(cur_file,input_path_spec) then goto done;
@z

@x
if term_offset+length(name)>max_print_line-2 then print_ln
@y
if term_offset+length(name)>max_print_line-3 then print_ln
@z

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% [29.537] get rid of return of name to string pool
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@x
if name=str_ptr-1 then {we can conserve string pool space now}
  begin flush_string; name:=cur_name;
  end;
@y
@z

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% [30.563] Fix TFM file opening
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@x
file_opened:=false;
if aire="" then pack_file_name(nom,TEX_font_area,".tfm")
else pack_file_name(nom,aire,".tfm");
if not b_open_in(tfm_file) then abort;
file_opened:=true
@y
file_opened:=false;
pack_file_name(nom,aire,".tfm");
if not b_open_in(tfm_file) then abort;
file_opened:=true
@z

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% [30.564] Reading the tfm file.  As a special case, whenever we open a
% tfm file, we read its first byte into `tfm_temp' right away.  TeX
% looks at `fbyte' before calling `fget', so it ends up seeing every
% byte.  This is Pascal-like I/O.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@x
@d fget==get(tfm_file)
@d fbyte==tfm_file^
@y
@d fget==tfm_temp:=getc(tfm_file)
@d fbyte==tfm_temp
@z

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% [31.585-586] new DVI opcodes (TeX-XeT extension)
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@x 
\yskip\noindent Commands 250--255 are undefined at the present time.

@ @d set_char_0=0 {typeset character 0 and move right}
@y
\yskip\hang|begin_reflect| 250. Begin a (possibly recursive) reflected segment.

\yskip\hang|end_reflect| 251. End a (possibly recursive) reflected segment.

\yskip\noindent Commands 250--255 are undefined in normal \.{DVI} files,
but 250 and 251 are permitted in the special `\.{DVI-IVD}' files
produced by this variant of \TeX.

@ @d begin_reflect=250 {begin a reflected segment (not normally allowed)}
@d end_reflect=251 {end a reflected segment (not normally allowed)}
@d set_char_0=0 {typeset character 0 and move right}
@z

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% [32.597] write_dvi
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@x
@ The actual output of |dvi_buf[a..b]| to |dvi_file| is performed by calling
|write_dvi(a,b)|. For best results, this procedure should be optimized to
run as fast as possible on each particular system, since it is part of
\TeX's inner loop. It is safe to assume that |a| and |b+1| will both be
multiples of 4 when |write_dvi(a,b)| is called; therefore it is possible on
many machines to use efficient methods to pack four bytes per word and to
output an array of words with one system call.
@^system dependencies@>
@^inner loop@>
@^defecation@>

@p procedure write_dvi(@!a,@!b:dvi_index);
var k:dvi_index;
begin for k:=a to b do write(dvi_file,dvi_buf[k]);
end;
@y
@ In C, we use a macro to call fwrite() or write() directly, writing all
the bytes to be written in one shot.  Much better even than writing four
bytes at a time.
@^system dependencies@>
@^inner loop@>
@^defecation@>
@z

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% [32.638] changes to ship_out (TeX-XeT extension)
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@x 
begin if tracing_output>0 then
@y
begin LR_ptr:=get_avail; info(LR_ptr):=0; {|begin_L_code| at outer level}
if tracing_output>0 then
@z
@x (module 639)
flush_node_list(p);
@y
flush_node_list(p); @<Flush the LR stack@>;
@z

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% [33.649] hpack changes (TeX-XeT extension)
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@x 
begin last_badness:=0; r:=get_node(box_node_size); type(r):=hlist_node;
@y
@!LR_ptr,@!LR_tmp:pointer; {for LR stack maintenance}
@!LR_problems:integer; {counts missing begins and ends}
begin LR_ptr:=null; LR_problems:=0; last_badness:=0;
r:=get_node(box_node_size); type(r):=hlist_node;
@z
@x (module 649, continued)
exit: hpack:=r;
@y
exit: @<Check for LR anomalies at the end of |hpack|@>;
hpack:=r;
@z

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% [38.859] Fix a C casting/expression evaluation problem
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@x
if abs(fit_class-fitness(r))>1 then d:=d+adj_demerits;
@y
if abs(toint(fit_class)-toint(fitness(r)))>1 then d:=d+adj_demerits;
@z

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% [39.875] Another casting bug
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@x
repeat if type(r)<>delta_node then
  begin line_diff:=line_number(r)-best_line;
@y
repeat if type(r)<>delta_node then
  begin line_diff:=toint(line_number(r))-toint(best_line);
@z

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% [39.877] post_line_break stuff (TeX-XeT extension)
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@x 
begin @<Reverse the links of the relevant passive nodes, setting |cur_p| to the
@y
@!LR_ptr,@!LR_tmp:pointer; {for LR stack maintenance}
begin LR_ptr:=null;
 @<Reverse the links of the relevant passive nodes, setting |cur_p| to the
@z
@x (module 877, continued)
prev_graf:=best_line-1;
@y
prev_graf:=best_line-1;
@<Flush the LR stack@>;
@z

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% [39.880] post_line_break stuff continued(TeX-XeT extension)
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@x (module 880)
@<Modify the end of the line to reflect the nature of the break and to include
  \.{\\rightskip}; also set the proper value of |disc_break|@>;
@y
@<Insert LR nodes at the beginning of the current line@>;
@<Adjust the LR stack based on LR nodes in this line@>;
@<Modify the end of the line to reflect the nature of the break and to include
  \.{\\rightskip}; also set the proper value of |disc_break|@>;
@<Insert LR nodes at the end of the current line@>;
@z

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% [43.?] Hack around the negative lower bound here.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@x
Statistics printed during a dump make it possible for users to tell
if this has happened.

@<Glob...@>=
@!init@! trie_op_hash:array[-trie_op_size..trie_op_size] of 0..trie_op_size;
@y
Statistics printed during a dump make it possible for users to tell
if this has happened.

@<Glob...@>=
@!init@! trie_op_hash:array[neg_trie_op_size..trie_op_size] of 0..trie_op_size;
@z

@x
var h:-trie_op_size..trie_op_size; {trial hash location}
@y
var h:neg_trie_op_size..trie_op_size; {trial hash location}
@z

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% [43.944] Fix a C casting/expression evaluation problem
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@x
begin h:=abs(n+313*d+361*v+1009*cur_lang) mod (trie_op_size+trie_op_size)
@y
begin h:=abs(toint(n)+313*toint(d)+361*toint(v)+1009*toint(cur_lang))
  mod (trie_op_size+trie_op_size)
@z

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% [43.947] Fix a C casting/expression evaluation problem
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@x
begin h:=abs(trie_c[p]+1009*trie_o[p]+@|
    2718*trie_l[p]+3142*trie_r[p]) mod trie_size;
@y
begin h:=abs(toint(trie_c[p])+1009*toint(trie_o[p])+@|
    2718*toint(trie_l[p])+3142*toint(trie_r[p])) mod trie_size;
@z

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% [47.1090] new horizontal command (TeX-XeT extension)
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@x 
   vmode+ex_space,vmode+no_boundary:@t@>@;@/
@y
   vmode+ex_space,vmode+no_boundary,vmode+LR:@t@>@;@/
@z

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% [48.1196] math in text is L-text (TeX-XeT extension)
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@x 
begin tail_append(new_math(math_surround,before));
@y
begin tail_append(new_math(math_surround,before));
@<Append a |begin_L| to the tail of the current list@>;
@z
@x (module 1196, continued)
tail_append(new_math(math_surround,after));
@y
@<Append an |end_L| to the tail of the current list@>;
tail_append(new_math(math_surround,after));
@z
  
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% [49.1275] a_open_in of \read file needs path specifier
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@x
  if a_open_in(read_file[n]) then read_open[n]:=just_open;
@y
  if a_open_in(read_file[n],read_path_spec) then read_open[n]:=just_open;
@z

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% [50.1302] Eliminate now-unused variable w in |store_fmt_file|.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@x
@!x: integer; {something to dump}
@!w: four_quarters; {four ASCII codes}
@y
@!x: integer; {something to dump}
@z

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% [50.1303] Eliminate now-unused variable w in |load_fmt_file|.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@x
@!x: integer; {something undumped}
@!w: four_quarters; {four ASCII codes}
@y
@!x: integer; {something undumped}
@z

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% [50.passim] Fix reading and writing fmt_file for C
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@x
@d dump_wd(#)==begin fmt_file^:=#; put(fmt_file);@+end
@d dump_int(#)==begin fmt_file^.int:=#; put(fmt_file);@+end
@d dump_hh(#)==begin fmt_file^.hh:=#; put(fmt_file);@+end
@d dump_qqqq(#)==begin fmt_file^.qqqq:=#; put(fmt_file);@+end
@y
@d dump_wd(#)==put_fmt_word(#)
@d dump_int(#)==put_fmt_int(#)
@d dump_hh(#)==put_fmt_hh(#)
@d dump_qqqq(#)==put_fmt_qqqq(#)
@z

@x
@d undump_wd(#)==begin get(fmt_file); #:=fmt_file^;@+end
@d undump_int(#)==begin get(fmt_file); #:=fmt_file^.int;@+end
@d undump_hh(#)==begin get(fmt_file); #:=fmt_file^.hh;@+end
@d undump_qqqq(#)==begin get(fmt_file); #:=fmt_file^.qqqq;@+end
@y
@d undump_wd(#)==get_fmt_word(#)
@d undump_int(#)==get_fmt_int(#)
@d undump_hh(#)==get_fmt_hh(#)
@d undump_qqqq(#)==get_fmt_qqqq(#)
@z

@x
x:=fmt_file^.int;
@y
get_fmt_int(x);		{This is reading the first word of the fmt file}
@z

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% [??] Make dumping/undumping more efficient in C
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@x
for k:=0 to str_ptr do dump_int(str_start[k]);
k:=0;
while k+4<pool_ptr do
  begin dump_four_ASCII; k:=k+4;
  end;
k:=pool_ptr-4; dump_four_ASCII;
@y
dump_things(str_start[0], str_ptr+1);
dump_things(str_pool[0], pool_ptr);
@z

@x
for k:=0 to str_ptr do undump(0)(pool_ptr)(str_start[k]);
k:=0;
while k+4<pool_ptr do
  begin undump_four_ASCII; k:=k+4;
  end;
k:=pool_ptr-4; undump_four_ASCII;
@y
undump_things(str_start[0], str_ptr+1);
undump_things(str_pool[0], pool_ptr);
@z

@x
repeat for k:=p to q+1 do dump_wd(mem[k]);
x:=x+q+2-p; var_used:=var_used+q-p;
p:=q+node_size(q); q:=rlink(q);
until q=rover;
var_used:=var_used+lo_mem_max-p; dyn_used:=mem_end+1-hi_mem_min;@/
for k:=p to lo_mem_max do dump_wd(mem[k]);
x:=x+lo_mem_max+1-p;
dump_int(hi_mem_min); dump_int(avail);
for k:=hi_mem_min to mem_end do dump_wd(mem[k]);
@y
repeat
 dump_things(mem[p], q+2-p);
x:=x+q+2-p; var_used:=var_used+q-p;
p:=q+node_size(q); q:=rlink(q);
until q=rover;
var_used:=var_used+lo_mem_max-p; dyn_used:=mem_end+1-hi_mem_min;@/
dump_things(mem[p], lo_mem_max+1-p);
x:=x+lo_mem_max+1-p;
dump_int(hi_mem_min); dump_int(avail);
dump_things(mem[hi_mem_min], mem_end+1-hi_mem_min);
@z

@x
repeat for k:=p to q+1 do undump_wd(mem[k]);
p:=q+node_size(q);
if (p>lo_mem_max)or((q>=rlink(q))and(rlink(q)<>rover)) then goto bad_fmt;
q:=rlink(q);
until q=rover;
for k:=p to lo_mem_max do undump_wd(mem[k]);
@y
repeat
  undump_things(mem[p], q+2-p);
p:=q+node_size(q);
if (p>lo_mem_max)or((q>=rlink(q))and(rlink(q)<>rover)) then goto bad_fmt;
q:=rlink(q);
until q=rover;
undump_things(mem[p], lo_mem_max+1-p);
@z

@x
for k:=hi_mem_min to mem_end do undump_wd(mem[k]);
@y
undump_things(mem[hi_mem_min], mem_end+1-hi_mem_min);
@z

@x
while k<l do
  begin dump_wd(eqtb[k]); incr(k);
  end;
@y
dump_things(eqtb[k], l-k);
@z

@x
while k<l do
  begin dump_wd(eqtb[k]); incr(k);
  end;
@y
dump_things(eqtb[k], l-k);
@z

@x
for j:=k to k+x-1 do undump_wd(eqtb[j]);
@y
undump_things(eqtb[k], x);
@z

@x
for p:=hash_used+1 to undefined_control_sequence-1 do dump_hh(hash[p]);
@y
dump_things(hash[hash_used+1], undefined_control_sequence-1-hash_used);
@z

@x
for p:=hash_used+1 to undefined_control_sequence-1 do undump_hh(hash[p]);
@y
undump_things(hash[hash_used+1], undefined_control_sequence-1-hash_used);
@z

@x
for k:=0 to fmem_ptr-1 do dump_wd(font_info[k]);
dump_int(font_ptr);
for k:=null_font to font_ptr do
  @<Dump the array info for internal font number |k|@>;
@y
@<Dump the array info for internal font number |k|@>;
@z

@x
for k:=0 to fmem_ptr-1 do undump_wd(font_info[k]);
undump_size(font_base)(font_max)('font max')(font_ptr);
for k:=null_font to font_ptr do
  @<Undump the array info for internal font number |k|@>
@y
@<Undump the array info for internal font number |k|@>;
@z

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% [50.1322] Writing font info (almost at end of dump stuff)
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Knuth's code writes all the information relevant to a single font
% in the same section of the fmt file.  But it's a lot faster to
% write the arrays of information out, one whole array at a time.
% So that's the way we handle dumping and undumping font info.
@x
@ @<Dump the array info for internal font number |k|@>=
begin dump_qqqq(font_check[k]);
dump_int(font_size[k]);
dump_int(font_dsize[k]);
dump_int(font_params[k]);@/
dump_int(hyphen_char[k]);
dump_int(skew_char[k]);@/
dump_int(font_name[k]);
dump_int(font_area[k]);@/
dump_int(font_bc[k]);
dump_int(font_ec[k]);@/
dump_int(char_base[k]);
dump_int(width_base[k]);
dump_int(height_base[k]);@/
dump_int(depth_base[k]);
dump_int(italic_base[k]);
dump_int(lig_kern_base[k]);@/
dump_int(kern_base[k]);
dump_int(exten_base[k]);
dump_int(param_base[k]);@/
dump_int(font_glue[k]);@/
dump_int(bchar_label[k]);
dump_int(font_bchar[k]);
dump_int(font_false_bchar[k]);@/
print_nl("\font"); print_esc(font_id_text(k)); print_char("=");
print_file_name(font_name[k],font_area[k],"");
if font_size[k]<>font_dsize[k] then
  begin print(" at "); print_scaled(font_size[k]); print("pt");
  end;
end
@y
@ @<Dump the array info for internal font number |k|@>=
begin dump_things(font_info[0], fmem_ptr);
dump_int(font_ptr);
dump_things(font_check[null_font], font_ptr+1-null_font);
dump_things(font_size[null_font], font_ptr+1-null_font);
dump_things(font_dsize[null_font], font_ptr+1-null_font);
dump_things(font_params[null_font], font_ptr+1-null_font);
dump_things(hyphen_char[null_font], font_ptr+1-null_font);
dump_things(skew_char[null_font], font_ptr+1-null_font);
dump_things(font_name[null_font], font_ptr+1-null_font);
dump_things(font_area[null_font], font_ptr+1-null_font);
dump_things(font_bc[null_font], font_ptr+1-null_font);
dump_things(font_ec[null_font], font_ptr+1-null_font);
dump_things(char_base[null_font], font_ptr+1-null_font);
dump_things(width_base[null_font], font_ptr+1-null_font);
dump_things(height_base[null_font], font_ptr+1-null_font);
dump_things(depth_base[null_font], font_ptr+1-null_font);
dump_things(italic_base[null_font], font_ptr+1-null_font);
dump_things(lig_kern_base[null_font], font_ptr+1-null_font);
dump_things(kern_base[null_font], font_ptr+1-null_font);
dump_things(exten_base[null_font], font_ptr+1-null_font);
dump_things(param_base[null_font], font_ptr+1-null_font);
dump_things(font_glue[null_font], font_ptr+1-null_font);
dump_things(bchar_label[null_font], font_ptr+1-null_font);
dump_things(font_bchar[null_font], font_ptr+1-null_font);
dump_things(font_false_bchar[null_font], font_ptr+1-null_font);
for k:=null_font to font_ptr do begin
  print_nl("\font"); print_esc(font_id_text(k)); print_char("=");
  print_file_name(font_name[k],font_area[k],"");
  if font_size[k]<>font_dsize[k] then begin
    print(" at "); print_scaled(font_size[k]); print("pt");
  end;
end;
end
@z

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% [50.1322] Reading font info for C (Nearly done with undump stuff)
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@x
@ @<Undump the array info for internal font number |k|@>=
begin undump_qqqq(font_check[k]);@/
undump_int(font_size[k]);
undump_int(font_dsize[k]);
undump(min_halfword)(max_halfword)(font_params[k]);@/
undump_int(hyphen_char[k]);
undump_int(skew_char[k]);@/
undump(0)(str_ptr)(font_name[k]);
undump(0)(str_ptr)(font_area[k]);@/
undump(0)(255)(font_bc[k]);
undump(0)(255)(font_ec[k]);@/
undump_int(char_base[k]);
undump_int(width_base[k]);
undump_int(height_base[k]);@/
undump_int(depth_base[k]);
undump_int(italic_base[k]);
undump_int(lig_kern_base[k]);@/
undump_int(kern_base[k]);
undump_int(exten_base[k]);
undump_int(param_base[k]);@/
undump(min_halfword)(lo_mem_max)(font_glue[k]);@/
undump(0)(font_mem_size)(bchar_label[k]);
undump(min_quarterword)(non_char)(font_bchar[k]);
undump(min_quarterword)(non_char)(font_false_bchar[k]);
end
@y
@  The way this is done in C makes the reference to
the internal font number meaningless, but putting the code
here preserves the association with the WEB modules.

@<Undump the array info for internal font number |k|@>=
begin undump_things(font_info[0], fmem_ptr);
undump_size(font_base)(font_max)('font max')(font_ptr);
undump_things(font_check[null_font], font_ptr+1-null_font);
undump_things(font_size[null_font], font_ptr+1-null_font);
undump_things(font_dsize[null_font], font_ptr+1-null_font);
undump_things(font_params[null_font], font_ptr+1-null_font);
undump_things(hyphen_char[null_font], font_ptr+1-null_font);
undump_things(skew_char[null_font], font_ptr+1-null_font);
undump_things(font_name[null_font], font_ptr+1-null_font);
undump_things(font_area[null_font], font_ptr+1-null_font);
undump_things(font_bc[null_font], font_ptr+1-null_font);
undump_things(font_ec[null_font], font_ptr+1-null_font);
undump_things(char_base[null_font], font_ptr+1-null_font);
undump_things(width_base[null_font], font_ptr+1-null_font);
undump_things(height_base[null_font], font_ptr+1-null_font);
undump_things(depth_base[null_font], font_ptr+1-null_font);
undump_things(italic_base[null_font], font_ptr+1-null_font);
undump_things(lig_kern_base[null_font], font_ptr+1-null_font);
undump_things(kern_base[null_font], font_ptr+1-null_font);
undump_things(exten_base[null_font], font_ptr+1-null_font);
undump_things(param_base[null_font], font_ptr+1-null_font);
undump_things(font_glue[null_font], font_ptr+1-null_font);
undump_things(bchar_label[null_font], font_ptr+1-null_font);
undump_things(font_bchar[null_font], font_ptr+1-null_font);
undump_things(font_false_bchar[null_font], font_ptr+1-null_font);
end
@z

% The hyphenation patterns.
% 
@x
for k:=0 to trie_max do dump_hh(trie[k]);
dump_int(trie_op_ptr);
for k:=1 to trie_op_ptr do
  begin dump_int(hyf_distance[k]);
  dump_int(hyf_num[k]);
  dump_int(hyf_next[k]);
  end;
@y
dump_things(trie[0], trie_max+1);
dump_int(trie_op_ptr);
dump_things(hyf_distance[1], trie_op_ptr);
dump_things(hyf_num[1], trie_op_ptr);
dump_things(hyf_next[1], trie_op_ptr);
@z

@x
for k:=0 to j do undump_hh(trie[k]);
undump_size(0)(trie_op_size)('trie op size')(j); @+init trie_op_ptr:=j;@+tini
for k:=1 to j do
  begin undump(0)(63)(hyf_distance[k]); {a |small_number|}
  undump(0)(63)(hyf_num[k]);
  undump(min_quarterword)(max_quarterword)(hyf_next[k]);
  end;
@y
undump_things(trie[0], j+1);
undump_size(0)(trie_op_size)('trie op size')(j); @+init trie_op_ptr:=j;@+tini
undump_things(hyf_distance[1], j);
undump_things(hyf_num[1], j);
undump_things(hyf_next[1], j);
@z

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% [50.1328] Eliminate possibly wrong word `preloaded' from format_idents.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@x
print(" (preloaded format="); print(job_name); print_char(" ");
@y
print(" (format="); print(job_name); print_char(" ");
@z

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% [51.1332] uexit() call depends on `history', procedureize the main
% programs, and add call to set_paths.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@x
@ Now this is really it: \TeX\ starts and ends here.

The initial test involving |ready_already| should be deleted if the
\PASCAL\ runtime system is smart enough to detect such a ``mistake.''
@y
@ Now this is really it: \TeX\ starts and ends here.

Use the value of |history| to determine what exit code to use.
@z

@x
@p begin @!{|start_here|}
history:=fatal_error_stop; {in case we quit during initialization}
t_open_out; {open the terminal for output}
if ready_already=314159 then goto start_of_TEX;
@y
@p procedure tex_body;
label @<Labels in the outer block@>@/
var bufindx:0..buf_size; {an index used in a for loop below}
begin @!{|start_here|}
history:=fatal_error_stop; {in case we quit during initialization}
t_open_out; {open the terminal for output}
set_paths; {get default file paths from the Unix environment}
if ready_already=314159 then goto start_of_TEX;
@z

@x
final_end: ready_already:=0;
end.
@y
final_end: do_final_end;
end {|tex_body|};
@z

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% [51.1333] Omit call to wake_up_terminal on normal termination.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@x
wake_up_terminal; @<Finish the \.{DVI} file@>;
@y
@<Finish the \.{DVI} file@>;
@z

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% [51.1333] Print new line before termination; switch to editor if necessary.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@x
    print(log_name); print_char(".");
    end;
  end;
@y
    print(log_name); print_char(".");
    end;
  end;
print_ln;
if (edit_name_start<>0) and (interaction>batch_mode) then
    calledit(str_pool,edit_name_start,edit_name_length,edit_line);
@z

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% [52.1338] Core-dump in debugging mode on 0 input.  Under Unix, it's
% not possible to switch into the debugger while a program is running.
% The best approximation is to do a core dump, then run the debugger on
% it later.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@x
    begin goto breakpoint;@\ {go to every label at least once}
    breakpoint: m:=0; @{'BREAKPOINT'@}@\
    end
@y
    dump_core {Do something to cause a core dump}
@z

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% [53.1341] whatsit processing (TeX-XeT extension)
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@x 
@d special_node=3 {|subtype| in whatsits that represent \.{\\special} things}
@y
@d special_node=3 {|subtype| in whatsits that represent \.{\\special} things}
@d LR_node=4 {|subtype| in whatsits that represent \.{\\beginL}, etc.}
@d LR_type(#)==mem[#+1].int {the sub-subtype}
@z

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% [53.1344] whatsit processing continued (TeX-XeT extension)
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@x 
@d immediate_code=4 {command modifier for \.{\\immediate}}
@d set_language_code=5 {command modifier for \.{\\setlanguage}}

@<Put each...@>=
@y
@d immediate_code=4 {command modifier for \.{\\immediate}}
@d set_language_code=5 {command modifier for \.{\\setlanguage}}
@d begin_L_code=0 {command modifier for \.{\\beginL}}
@d begin_R_code=1 {command modifier for \.{\\beginR}}
@d end_L_code=2 {command modifier for \.{\\endL}}
@d end_R_code=3 {command modifier for \.{\\endR}}
@d begin_LR(#)==(LR_type(#)<end_L_code)
@d begin_LR_type(#)==(LR_type(#)-end_L_code)

@<Put each...@>=
primitive("beginL",LR,begin_L_code);@/
@!@:begin_L_}{\.{\\beginL} primitive@>
primitive("beginR",LR,begin_R_code);@/
@!@:begin_R_}{\.{\\beginR} primitive@>
primitive("endL",LR,end_L_code);@/
@!@:end_L_}{\.{\\endL} primitive@>
primitive("endR",LR,end_R_code);@/
@!@:end_R_}{\.{\\endR} primitive@>
@z

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% [53.1346] whatsit processing continued (TeX-XeT extension)
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@x (module 1346)
@ @<Cases of |print_cmd_chr|...@>=
@y
@ @<Cases of |print_cmd_chr|...@>=
LR: case chr_code of
begin_L_code: print_esc("beginL");
begin_R_code: print_esc("beginR");
end_L_code: print_esc("endL");
othercases print_esc("endR")
endcases;
@z

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% [53.1356] whatsit processing continued (TeX-XeT extension)
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@x (module 1356)
othercases print("whatsit?")
@y
LR_node: case LR_type(p) of
begin_L_code: print_esc("beginL");
begin_R_code: print_esc("beginR");
end_L_code: print_esc("endL");
othercases print_esc("endR")
endcases;
othercases print("whatsit?")
@z
@x (module 1357)
close_node,language_node: begin r:=get_node(small_node_size);
  words:=small_node_size;
  end;
@y
close_node,language_node,LR_node: begin r:=get_node(small_node_size);
  words:=small_node_size;
  end;
@z
@x (module 1358)
close_node,language_node: free_node(p,small_node_size);
@y
close_node,language_node,LR_node: free_node(p,small_node_size);
@z

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% [53.1360] whatsit processing continued (TeX-XeT extension)
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@x (module 1360)
@ @<Incorporate a whatsit node into an hbox@>=do_nothing
@y
@ @<Incorporate a whatsit node into an hbox@>=
if subtype(p)=LR_node then @<Adjust the LR stack for the |hpack| routine@>
@z

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% [53.1366] whatsit processing continued (TeX-XeT extension)
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@x (module 1366)
@ @<Output the whatsit node |p| in an hlist@>=
out_what(p)
@y
@ @<Output the whatsit node |p| in an hlist@>=
if subtype(p)<>LR_node then out_what(p)
else @<Output a reflection instruction if the direction has changed@>
@z

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% [54.1376] add TeX-XeT extensions 
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@x Final system-dependent changes: [1376]
This section should be replaced, if necessary, by any special
modifications of the program
that are necessary to make \TeX\ work at a particular installation.
It is usually best to design your change file so that all changes to
previous sections preserve the section numbering; then everybody's version
will be consistent with the published program. More extensive changes,
which introduce new sections, can be inserted here; then only the index
itself will get a new section number.
@^system dependencies@>
@y
Now we do the main work required for mixed-direction texts.

@<Cases of |main_control| that build...@>=
hmode+LR: begin new_whatsit(LR_node,small_node_size); LR_type(tail):=cur_chr;
  end;
mmode+LR: report_illegal_case;

@ @<Glob...@>=
@!LR_ptr,@!LR_tmp:pointer; {stack of LR codes and temp for manipulation}

@ @<Declare functions needed for special kinds of nodes@>=
function new_LR(@!s:small_number): pointer;
var p: pointer; {the new node}
begin p:=get_node(small_node_size); type(p):=whatsit_node; subtype(p):=LR_node;
LR_type(p):=s; new_LR:=p;
end;

@ @<Declare functions needed for special kinds of nodes@>=
function safe_info(@!p:pointer): integer;
begin if p=null then safe_info:=-1@+else safe_info:=info(p);
end;

@ @<Append a |begin_L| to the tail of the current list@>=
tail_append(new_LR(begin_L_code))

@ @<Append an |end_L| to the tail of the current list@>=
tail_append(new_LR(end_L_code))

@ A number of routines are based on a stack of one-word nodes whose |info|
fields contain either |begin_L_code| or |begin_R_code|. The top of the
stack is pointed to by |LR_ptr|, and an auxiliary variable |LR_tmp| is
available for stack manipulation.

@d push_LR(#)==begin LR_tmp:=get_avail; info(LR_tmp):=LR_type(#);
  link(LR_tmp):=LR_ptr; LR_ptr:=LR_tmp;
  end
@d pop_LR==begin LR_tmp:=LR_ptr; LR_ptr:=link(LR_tmp); free_avail(LR_tmp);
  end

@<Flush the LR stack@>=while LR_ptr<>null do pop_LR

@ @<Insert LR nodes at the beginning of the current line@>=
while LR_ptr<>null do
  begin LR_tmp:=new_LR(info(LR_ptr)); link(LR_tmp):=link(temp_head);
  link(temp_head):=LR_tmp; pop_LR;
  end

@ @<Adjust the LR stack based on LR nodes in this line@>=
q:=link(temp_head);
while q<>cur_break(cur_p) do
  begin if not is_char_node(q) then if type(q)=whatsit_node then
   if subtype(q)=LR_node then
    if begin_LR(q) then push_LR(q)
    else if LR_ptr<>null then
     if info(LR_ptr)=begin_LR_type(q) then pop_LR;
  q:=link(q);
  end

@ We use the fact that |q| now points to the node with \.{\\rightskip} glue.

@<Insert LR nodes at the end of the current line@>=
if LR_ptr<>null then
  begin s:=temp_head; r:=link(s);
  while r<>q do
    begin s:=r; r:=link(s);
    end;
  r:=LR_ptr;
  while r<>null do
    begin LR_tmp:=new_LR(info(r)+end_L_code);
    link(s):=LR_tmp; s:=LR_tmp; r:=link(r);
    end;
  link(s):=q;
  end

@ @<Adjust the LR stack for the |hpack| routine@>=
if begin_LR(p) then push_LR(p)
else if safe_info(LR_ptr)=begin_LR_type(p) then pop_LR
else  begin incr(LR_problems);
  while link(q)<>p do q:=link(q);
  link(q):=link(p); free_node(p,small_node_size); p:=q;
  end

@ @<Check for LR anomalies at the end of |hpack|@>=
if LR_ptr<>null then
  begin while link(q)<>null do q:=link(q);
  repeat link(q):=new_LR(info(LR_ptr)+end_L_code); q:=link(q);
  LR_problems:=LR_problems+10000; pop_LR;
  until LR_ptr=null;
  end;
if LR_problems>0 then
  begin print_ln; print_nl("\endL or \endR problem (");@/
  print_int(LR_problems div 10000); print(" missing, ");@/
  print_int(LR_problems mod 10000); print(" extra");@/
  LR_problems:=0; goto common_ending;
  end

@ @<Output a reflection instruction if the direction has changed@>=
if begin_LR(p) then
  begin if safe_info(LR_ptr)<>LR_type(p) then
    begin synch_h; synch_v; dvi_out(begin_reflect);
    end;
  push_LR(p);
  end
else if safe_info(LR_ptr)=begin_LR_type(p) then
  begin pop_LR;
  if info(LR_ptr)+end_L_code<>LR_type(p) then
    begin synch_h; synch_v; dvi_out(end_reflect);
    end;
  end
else confusion("LR")
@:this can't happen LR}{\quad LR@>

@ Finally we get to a small addition that has nothing to do with LR nodes.

Here is a temporary integer, used as a holder during reading and writing of
TFM files, and a temporary memory_word, used in reading/writing format
files.
Also, the variables used to hold ``switch-to-editor'' information.
@^<system dependencies@>

@<Glob...@>=
@!edit_name_start: pool_pointer;
@!edit_name_length,@!edit_line,@!tfm_temp: integer;

@ The |edit_name_start| will be set to point into |str_pool| somewhere after
its beginning if \TeX\ is supposed to switch to an editor on exit.

@<Set init...@>=
edit_name_start:=0;
@z
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